---
title: No-Mutation Principle
description: Why Papra never modifies your original documents and the architectural decisions behind this choice.
slug: architecture/no-mutation-principle
---

## Core Philosophy

Papra follows a fundamental principle: **documents are never mutated after upload**. When you input a document, you can always retrieve it exactly as it was uploaded.

## The Design Choice

An archiving platform should guarantee users they can retrieve their documents in their original form. This means:

- No conversion to different formats
- No metadata injection into the file itself
- No overlay of OCR-ed content on scanned PDFs
- No processing that modifies the original file

The simple mental model is: **"If I input X, I'll retrieve X"**

## Why This Matters

### Trust and Reliability

When archiving important documents, users need absolute confidence that their files remain untouched. Whether it's a legal document, a medical record, or a personal photo, the original should be sacrosanct.

### Simplicity

This approach eliminates the mental overhead of wondering "what happened to my file?" Users don't need to understand concepts like:
- Original vs. processed versions
- Format conversions
- OCR overlays
- Metadata injection

### Flexibility for the Future

While Papra currently doesn't mutate documents, the architecture leaves room for future enhancements. If needed, a "processed" version concept could be added alongside originals, giving users the choice without forcing a particular model.
